Method for reclaiming scrap metal



Patented Oct. 11, i932 scrap from bearings consists of a mechanlcal mlxture of umrsn STATES PATENT;- OFFICE HAERY VJ. THOMAS, JR., 0F BIRMINGHAM, MICHIGAN METHOD FOR BECLAIMTNG SCRAP METAL i No Drawing. Application filed March 5,

This invention relates to methods for reclaiming scrap metal and, more particularly,

to the reclamation of Babbitt bronze scrap.

It is a common practice in the manufacture and repair of machinery to employ, as bearings or journals for rotating shafts, or the like, bearing or journal boxes, and caps therefor, constructed of a relatively hard metal such as bronze, brass, or the like, with which is combined a softer metal, such as Babbitt metal, the latter sometimes being poured into grooves or recesses in the bronze to form inlays, so that the surface presented to the rotating shaft is partially bronze and partially Babbitt metal. After the Babbitt metal is associated with the bronze, or other harder metal, the bearing is bored, or otherwise machined, to the required dimensions. During the machining the chips cut off by the tool are usually collected in the usual chip pan of the machine tool. It is standard machine shop practice to salvage the chips and sell the same as junk, but owing to the fact that the chip the machining of Babbitt bronze soft Babbitt metal with the harder bronze, such scrap has no market value unless the soft and hard metals are separated. No purely mechanical means can be employed for effecting the desired separation, nor can the electromagnetic devices such as are used for separating steel and iron from brass or babbitt be used, as both bronze and babbitt are nonmagnetic materials.

Purely chemical treatments of the Babbitt bronze mixtures to obtain the desired separation are not commercially practicable because of the prohibitive cost of such treatments. In View of the above factors, relatively large amounts of Babbitt bronze scraps, annually go to waste, and the disposal of such scrap instead of forming a source of revenue, as it would if separated into its constituents. becomes a source of expense and in some cases a difiieult and bothersome problem.

The principal object of the present invention is to provide a simple and inexpensive method of treatment for Babbitt bronze scrap, for carrying out such method, whereby 1931. Serial to. 520,483.

the babbitt and bronze may be effectively separated, without the necessity of subjecting the scrap to any chemical treatment.

A further object is to provide a new and improved Babbitt metal from bronze or other particles in mechanical mixtures, which method depends upon a simple flotation process combined with an inexpensive and simple treatment of the scrap or other mixture as a pre- L liminary step that will insure an effective separation during the flotation step.

In accordance with the present invention the scrap or other mixture to be separated is screened and graded, for example, mesh, 35 mesh and 50 mesh mixtures, this screening and grading being resorted to because the time of treatment of the scrap mixtures, presently to be described, can be regulated according to the fineness of the particles and in addition the efliciency of separation and percentage of recovery increased if the size of the particles in any particular batch to be treated are substantially uniform.

After screening andgrading a quantity of 7 the material is placed in any suitable agitator and mixed with a small amount of'oil, an inexpensive machine oil of relatively low, viscosity being suitable. After the surfaces of the particles have been covered with a'thin film of oil the material is transferred to a water tank'and agitated therein. During the agitation of the material in the water tank, any suitable oxidizing agent is introduced into the tank, preferably compressed the purpose of oxidizing the bronze particles. After the surface oxidation of the bronze particl'esis effected the material is then transferred to a flotation chamber or machine in which the particles ofBabbitt metal will re- 90 main on the surface and the bronze particles will sink. The Babbitt partic] cs may befloated or skimmed off. After substantiallycom pleteseparation the water may be drawn ofi" and-the bronze particles removed. I

The process depends for itsefficiency upon a number of factors among'which maybe stated that the Babbitt metalcontains antimony as a constituent inv solid solution, with tin and copper. Theoilhas a greater aflinity' method for separating particles of I linto 20 ,06

air, for i 10 the. flotation chamber,

material is agitated with oil a thin film of oil adheres to the particles of Babbitt metal but not to the particles of bronze. When the ma 5 terial is placed in the water tank and agitated with an oxidizing agent the bronze particles become oxidized, while the film of oil on the Babbitt particles prevent their oxidation. Finally when the material is transferred to the separation is effected by the Babbitt metal particles floating ion the surface while the bronze particlessink due to the surface oxidation of-the bronze increasing the Wettability of the bronze partition treatment to separate the antimonyalloy particles from the non-antimony alloy particles.

2. A process of separating scrap material comprising particles of antimony alloy, and particles of non-antimony alloy, agitating said material with a substance to form a procles while the oil film decreases the wettability of the Babbitt particles. The separation by the. flotation process therefore depends more up'on skin or surface tension flotation rather than froth flotation.

2Q? I have by the use of the above process succeeded in securing from 96 to 98% separation whichfor commercial purposes may be con sidered complete separation, as the small per centage unseparated is negligible as far as zg any practical deteriorating effect on the recovered materials is concerned. c

It will be understood that any suitable apparatus may be used for carrying outthe steps of the method, for example, the agitation 3g-with oil may be done in a rotating drum or tumbler or any other suitable device, agitation in the water tank may be effected by one or more jets, a plurality of small jets introduced from the bottom of the tank being a aawsuitable expedient, or, if preferred the agitation may be effected by employing compressed air for oxidizingto produce the agitation by jet effects of the air. (The flotation chamber or machine may also be of any suits 40,-able construction.) The amount of oil to be 7 used and the time of treatment in the oil coating step as well as thetime of treatment in the oxidizing and flotation steps will of course vary with the quantity of material to be 45 treated.

While. I have referred throughout the above description to the material to be treated as bronze babbitt,itwill beunderstood that the terms bronze and babbitt are used 5Q merely as illustrative and not in a specific limitative sense. It will also be understood that, while I have referred to the use of machine oil for the first steps, any equivalent substance, capable of forming aprotective 5 -oz; idization resistant coating on the particles of one of the constituent metals may be employed instead of oil. Likewise other changes, variations and modifications may be resorted to. without departing from the principles of my invention.

Having thus described my invention, what I claim as, new and desire to. secure by Letters Patent of the United States is:

1 A process of separating scrap material '95.- comprising particles of antimony alloy and tective, oxidization resistant, coating on'the antimony alloy particles, then placing Said material in a water bath said bath while introducing therein an oxizi g" g nt, and nal y bjec ng said. ma: terial to a water, surface tension flotation process to separate the antimony alloy particles from the non-antimony alloy particles.

In testimony whereof I aff x signature hereto.

' HARRY W. THOMAS, JR,

and agita ing itn, 

